The K24 Mid-Career Mentoring and Research Award has permitted me to establish one of the few Musculoskeletal and Orthopaedic Clinical Research Training Programs and Research Units in the US. During the period of the award, I have published 68 papers, most as senior author, received six grants as Principal Investigator, and worked with over 25 mentees. My trainees have received two K23 awards, an R03 grant, and three other career development awards. All of this work has centered on musculoskeletal disorders and orthopaedic interventions. In this competitive renewal application, I request five additional years of K24 funding to enlarge and strengthen the mentoring and research programs. Specifically, I aim: 1. To further develop a clinical research-training program that will prepare the next generation of clinical investigators for rigorous study of musculoskeletal conditions and orthopaedic interventions, and will develop the next generation of mentors in clinical and musculoskeletal and orthopaedic research. 2. To expand my patient-oriented research rogram. In addition to continuing work on total hip and knee arthroplasty, and spinal and upper extremity disorders, I propose to critically evaluate the role of arthroscopic partial meniscectomy (APM) in patients with symptomatic meniscal tear and concomitant knee osteoarthritis. We plan a randomized controlled trial of APM as compared with a rigorous nonoperative regimen in 340 patients in five or six centers. The trial will evaluate the efficacy and cost effectiveness of APM as compared to nonoperative therapy and identify predictors of outcome. The trial, as well as my other research programs, will provide rich mentored research opportunities for trainees.